The present invention relates to a drive axle suspension system in a motor vehicle.
It has often been experienced that, upon variation in power output torque of a vehicle engine resulting from depression of an acceleration pedal, a vibrating system comprising an inertia of an engine flywheel, a relative twisting rigidity and damped oscillation of the suspension system including a drive system and wheels, and the mass of the vehicle, tends to be oscillated with consequent forward and backward oscillation occurring in the vehicle. Particularly in the case where a motor vehicle has a rear drive axle suspension system of the four-link suspension type with or without a Panhard rod in combination with radial-ply tires mounted on the wheels, attenuation of the vibrating system is so small that, upon sudden variation in the engine power output torque, uncomfortable and undesirable forward and backward oscillation tends to be prolonged.
In order to substantially avoid or minimize such forward and backward oscillation, it has heretofore been proposed to provide a hydraulic coupling in the vibrating system of the motor vehicle for taking the variation of the engine power output torque effectively. However, it has been found that the hydraulic coupling itself is expensive and, therefore, tends to increase the cost of manufacturing the motor vehicle.
The U.S. Pat. No. 3,444,947, patented on May 20, 1969, discloses a drive axle suspension system wherein resilient snubbers are used to resiliently resist wind-up of a drive axle housing induced by acceleration of the vehicle, which wind-up involves an unacceptably large upward movement of the drive shaft and differential housing. Although the purpose of the invention of the above described U.S. Patent is quite different from that of the present invention, the concept of the present invention can equally be applicable to the drive axle suspension system disclosed in the above described U.S. Patent.